The find - whose origin is murky - is about the size of a legal pad, with a 15-line inscription in ancient Hebrew that strongly resembles descriptions in the Bible's Book of Kings. It could also strengthen Jewish claims to a disputed holy site in Jerusalem's Old City that is now home to two major mosques.
Muslim clerics insist, despite overwhelming archaeological evidence, that no Jewish shrine ever stood at the site. That claim was made by Palestinian officials in failed negotiations with Israel in 2000 over who would be sovereign there.
The origin of the stone tablet is unclear, making it difficult to establish authenticity.
The Israeli daily Haaretz on Monday quoted an unidentified source as saying it was uncovered in recent years, during renovations carried out by the Muslim administrators of the mosque compound known to Muslims as the Haram as-Sharif, or Noble Sanctuary, and to Jews as the Temple Mount.
From there, it reached a major antiquities collector in Jerusalem, Haaretz said. The Holy Land has a thriving trade in antiquities, often operating on the edge of the law.
The sandstone tablet has a 15-line inscription in ancient Hebrew that resembles descriptions in Kings II, 12:1-6, 11-17, said Israel's Geological Survey, which examined the artifact. The words refer to King Joash, who ruled the area 2,800 years ago.
In it, the king tells priests to take "holy money ... to buy quarry stones and timber and copper and labor to carry out the duty with faith." If the work is completed well, "the Lord will protect his people with blessing," reads the last sentence of the inscription.
The Jerusalem collector has declined to come forward, and David Zailer, a lawyer for the collector, would not say where the tablet was found or give any further details.
Gabriel Barkai, a biblical archaeologist, said the collector asked the Israel Museum to determine the authenticity of the inscription and was told the museum's experts could not rule out a forgery. The Israel Museum declined comment Monday.
The collector then took the tablet to Israel's Geological Institute, whose experts studied it over the past year. "Our findings show that it is authentic," said Shimon Ilani, who performed geological tests on the inscription. Carbon dating confirms the writing goes back to the 9th century B.C., he said.
In the outer layer, Ilani and his colleagues found microscopic flecks of gold that could have been burnt into the stone when a building containing both the tablet and gold objects was destroyed.
This could mean the tablet was actually part of Solomon's Temple, which was destroyed by the Babylonians in 586 B.C., said Amos Bean, director of the institute.
"These specks of gold are not natural material, but a sign of human activity," said Bean. "They could be from gold-plated objects in the home of a very rich man, or a temple. ... It's hard to believe that anyone would know how to do these things to make it look real."
The stone itself was probably from the Dead Sea area and was originally whiter than its current dark gray, Bean said.
Hershel Shanks, editor of the Washington-based Biblical Archaeology Review, said the tablet, if authentic, would be "visual, tactile evidence that reaches across 2,800 years."
Barkai said the inscription's resemblance to biblical passages "has far-reaching implications of the historical importance of the biblical text."
Several other inscriptions excavated in recent years refer to characters or events from the Bible. A stone inscription found in northern Israel includes the phrase "house of David." Most experts consider this to be the first ancient writing outside the Bible that refers to King David or the Davidic line of kings, which has corroborated the basic history of the Hebrew Scriptures.
Adnan Husseini, the director of the Islamic Trust that administers the Jerusalem mosque compound, denied Monday the tablet was found during renovation work there.
In recent years, the Islamic Trust has turned an underground vault in the compound into a large prayer area, prompting complaints by Israeli archaeologists that important artifacts are being destroyed. At one point, the archaeologists said truckloads of soil from the holy site were dumped un-inspected into the nearby Kidron Valley.
The mosque compound is Islam's third-holiest site, while the adjacent Western Wall, the last remnant of the second Jewish Temple compound, is Judaism's holiest site. Most rabbis ban Jews from entering the Temple Mount for religious purity reasons.
When Israel conquered east Jerusalem in the 1967 Mideast war, it permitted Muslim clergy to continue administering the hilltop area to avoid conflict with the Muslim world.
The mystery surrounding the stone tablet - its murky origins, appearance on the private antiquities market and a collector unwilling to come forward - mirrors the controversy over an inscription on an ancient burial box that may be the oldest archaeological link to Jesus.
The burial box, or ossuary, had the inscription, "James, son of Joseph, brother of Jesus," leading some to believe it was used to store the remains of James, the brother of Jesus of Nazareth. Other experts said the inscription might be a forgery.
By Laurie Copans